Communications device and methods

ABSTRACT

A communications device, and method, is configured with at least one of an indication of first communications resources of the wireless access interface which can be allocated on request to the communications device by a mobile communications network for transmitting signals in one or more other communications devices in accordance with the first mode of operation or an indication of second communications resources of the wireless access interface, which can be used by the communications device for transmitting signals to one or more other communications devices in accordance with a second mode of operation using a device to device communications protocol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/126,058, filed on Sep. 14, 2016, which is a National Stage Entry ofInternational Patent Application No. PCT/EP2015/055855, filed on Mar.19, 2015, and claims priority to European Patent Application 14161201.0,filed in the European Patent Office on Mar. 21, 2014, the entirecontents of which is hereby incorporated herein by reference in itsentirety.

TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates to communications devices and methods forcommunicating data using communications devices, and in particular tocommunications devices which are configured to perform device-to-devicecommunications.

BACKGROUND OF THE DISCLOSURE

Mobile telecommunication systems, such as those based in the 3GPPdefined UMTS and Long Term Evolution (LTE) architecture, are able tosupport more sophisticated services than simple voice and messagingservices offered by previous generations of mobile telecommunicationsystems. For example, with the improved radio interface and enhanceddata rates provided by LTE systems, a user is able to enjoy high datarate applications such as video streaming and video conferencing onmobile communications devices that would previously only have beenavailable via a fixed line data connection.

The demand to deploy fourth generation networks is therefore strong andthe coverage area of these networks, i.e. geographic locations whereaccess to the networks is possible, is expected to increase rapidly.However, although the coverage and capacity of fourth generationnetworks is expected to significantly exceed those of previousgenerations of communications networks, there are still limitations onnetwork capacity and the geographical areas that can be served by suchnetworks. These limitations may, for example, be particularly relevantin situations in which networks are experiencing high load and high-datarate communications between communications devices, or whencommunications between communications devices are required but thecommunications devices may not be within the coverage area of a network.In order to address these limitations, in LTE release-12 the ability forLTE communications devices to perform device-to-device (D2D)communications will be introduced.

D2D communications allow communications devices that are in closeproximity to directly communicate with each other, both when within andwhen outside of a coverage area or when the network fails. This D2Dcommunications ability can allow user data to be more efficientlycommunicated between communications devices by obviating the need foruser data to be relayed by a network entity such as a base station, andalso allows communications devices that are in close proximity tocommunicate with one another although they may not be within thecoverage area of a network. The ability for communications devices tooperate both inside and outside of coverage areas makes LTE systems thatincorporate D2D capabilities well suited to applications such as publicsafety communications, for example. Public safety communications requirea high degree of robustness whereby devices can continue to communicatewith one another in congested networks and when outside a coverage area.

Fourth generation networks have therefore been proposed as a costeffective solution to public safety communications compared to dedicatedsystems such as TETRA, which, are currently used throughout the world.However, the potential coexistence of conventional LTE communicationsand D2D communications within a single coverage area or network mayincrease the complexity of coordinating communications and resourceallocation within a LTE network. In some applications a D2Dcommunication must be performed urgently and so there may be arequirement to provide an arrangement in which a communications devicecan access communications resources without suffering congestion as aresult of communications resources consumed by other communicationsdevices.

SUMMARY OF THE DISCLOSURE

According to a first example embodiment of the present technique thereis provided a method of communicating using a communications device viaa wireless access interface to perform device-to-device communications.The method comprises configuring the communications device with at leastone of an indication of one or more first communications resources ofthe wireless access interface which can be allocated on request to thecommunications device by a mobile communications network fortransmitting signals to one or more communications devices or receivingsignals from the one or more other communications devices in accordancewith the first mode of operation, when the communications device iswithin a coverage area provided by the mobile communications network,and an indication of one or more second communications resources of thewireless access interface which can be used by the communications devicefor transmitting signals to one or more other communications devices orreceiving signals from the one or more other communications devices inaccordance with a second mode of operation using a device to devicecommunications protocol, when the communications device is within thecoverage area provided by the mobile communications network. Theconfiguring of the communications device with the indication of thefirst and/or second communications resources may include pre-configuringthe communications device during manufacture or receiving at thecommunications device information relating to the configuration of thefirst and second communications resources. The method further includesreceiving, from the mobile communications network, an indication ofwhether the communications device can use at least one of the firstcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation or the second communications resources of the wireless accessinterface for performing device to device communications in accordancewith the second mode of operation, and depending on the indicationprovided by the mobile communications network and the configuration ofthe first communications resources and/or the second communicationsresources, transmitting signals to the one or more other communicationsdevices via the first communications resources allocated by the mobilecommunications network in accordance with a first mode of operation orreceiving signals from the one or more other communications devices viathe first communications resources, or transmitting signals to the oneor more other communications devices via the second communicationsresources or receiving signals from the one or more other communicationsdevices via the second communications resources in accordance with thesecond mode of operation using the device to device communicationsprotocol.

Embodiments of the present technique can provide an arrangement forrestricting or controlling communications devices, which are performingD2D communications so as to reduce or restrict access to communicationsresources for D2D communications in accordance with a priority given tothe communications devices. The control may be initiated for example asa result of an emergency situation so that a priority can be given tocommunications devices performing D2D communications for supportingemergency services for example. In other examples access may berestricted to D2D communications resources in order to manage congestionfor accessing the D2D communications resources.

According to some examples embodiments can provide an arrangement forsupporting different types or classes of UEs, which are performing D2Dcommunications. However, in order to support higher priority UEs such aspublic safety devices, in high load scenarios and/or high interferencescenarios it may be necessary to provide some discrimination in theaccess to D2D communications resources.

Mobile communications networks conventionally include an arrangement foraccess control barring in which congestion is controlled. In accordancewith an access probability value which is different for differentclasses of communications devices. Some embodiments of the presenttechnique are arranged to combine the previously proposed access controlbarring with the access control indication for D2D communications, tothe effect access control for D2D communications devices can be providedwith a greater level of granularity for different classes of thecommunications devices.

Embodiments of the present technique can provide one or more sections orpools of communications resources, each pool of resources beingassociated with a resource allocation mode and may also be associatedwith additional parameters specifying which types or classes ofcommunications devices are allowed to access those communicationsresources. This arrangement therefore provides an association of barringinformation/access rights with D2D communications resource pack and/ormodes of communication.

In same examples the indications received by the communications deviceof whether the communications device can use at least one of

the first communications resources of the wireless access interface forperforming device-to-device communications in accordance with the firstmode of operation, and

the second communications resources of the wireless access interface forperforming device to device communications in accordance with the secondmode of operations is dependent upon one of a plurality of predeterminedclasses of communications devices.

Various further aspects, and features of the present disclosure aredefined in the appended claims and include a communications device, amethod of communicating using a communications device.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the preset disclosure will now be described by way ofexample only with reference in the accompanying drawings wherein likeparts are provided with corresponding reference numerals and in which:

FIG. 1 provides a schematic diagram of a mobile communications system;

FIG. 2 provides a schematic diagram of the structure of a downlink of awireless access interface of a mobile communications system;

FIG. 3 provides a schematic diagram of an uplink of a wireless accessinterface of a mobile communications system:

FIG. 4 provides a schematic diagram of a mobile communications systemsin which communications devices can perform device-to-devicecommunications;

FIGS. 5a to 5d provides schematics diagrams of example device-to-devicecommunications scenarios;

FIG. 6 provides a schematic block diagram illustrating an arrangement inwhich a plurality of communications devices form a group which performdevice-to-device communications within a coverage area provided by amobile communications network referred to mode 1 in the presentdisclosure;

FIG. 7 is a flow diagram representing an example operation ofcommunications device performing device to device communications in apress-to-talk (PTT) application when in a coverage area provided by amobile communications network as represented in FIG. 6;

FIG. 8 provides a schematic block diagram illustrating an arrangement inwhich a plurality of communications devices form a group which performdevice-to-device communications outside a coverage area provided by amobile communications network and therefore operate autonomously whichis referred to mode 2 in the present disclosure;

FIG. 9 is a flow diagram representing an example operation ofcommunications device performing device to device communications in apress-to-talk (PTT) application when outside a coverage area provided bya mobile communications network as represented in FIG. 8;

FIG. 10 is a schematic block diagram representing a plurality ofcommunications devices performing D2D communications using differentpools of communications resources and different multiple access modes:

FIG. 11 is a message flow diagram representing an operation of acommunications system according to an example of the present technique,in which a communications device is signalled access rights for resourceallocation to a mode 2 D2D operation;

FIG. 12 is a message flow diagram representing an operation a of acommunications system according to an example of the present technique,in which a communications device is signalled access rights for resourceallocation in a mode 1 D2D operation;

FIG. 13 is a flow diagram representing an example operation of aninfrastructure equipment to communicate access restriction informationto communications devices according to the present technique;

FIG. 14 is a flow diagram representing an example operation of aninfrastructure equipment to communicate access restriction informationto communications devices, when the conditions for network accesschange, according to the present technique;

FIG. 15 is a flow diagram representing an example separation of acommunications device performing D2D communications using access controlinformation, according to the present technique; and

FIG. 16 is a schematic representation of a wireless access interfacecomprising a scheduling assignment region and regions sharedcommunications resources and illustrating an operation in accordancewith the present technique for supporting device-to-devicecommunications.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Conventional Communications System

FIG. 1 provides a schematic diagram of a conventional mobiletelecommunications system 106, where the system includes mobilecommunications devices 101, infrastructure equipment 102 and a corenetwork 103. Use infrastructure equipment may also be referred to as abase station, network element, enhanced Node B (eNodeB) or acoordinating entity for example, and provides a wireless accessinterface to the one or more communications devices within a coveragearea or cell. The one or more mobile communications devices maycommunicate data via the transmission and reception of signalsrepresenting data using the wireless access interface. The networkentity 102 is communicatively linked to the core network 103 where thecore network may be connected to one or more other communicationssystems or networks which have a similar structure to that formed fromcommunications devices 101 and infrastructure equipment 102. The corenetwork may also provide functionality including authentication,mobility management, charging and so on for the communications devicessensed by the network entity. The mobile communications devices of FIG.1 may also be referred to as communications terminals, user equipment(UE), terminal devices and so forth, and are configured to communicatewith one or more other communications devices served by the same or adifferent coverage area via the network entity. These communications maybe performed by transmitting and receiving signals representing datausing the wireless access interface over the two way communicationslinks represented by lines 104 to 109, where 104, 106 and 108 representdownlink communications from network entity to the communicationsdevices and 105, 107 and 109 represent the uplink communications fromthe communications devices to the network entity. The communicationssystem 100 may operate in accordance with any known protocol, forinstance in some examples the system 100 may operate in accordance withthe 3GPP Long Term Evolution (LTE) standard where the network entity andcommunications devices are commonly referred to as eNodeB and UEs,respectively.

FIG. 2 provides a simplified schematic diagram of the structure of adownlink of a wireless access interface that may the provided by or inassociation with the eNodeB of FIG. 1 when the communications system isoperating in accordance with the LTE standard. In LTE systems thewireless access interface of the downlink from an eNodeB to a UE isbased upon an orthogonal frequency division multiplexing (OFDM) accessradio interface. In an OFDM interface the resources of the availablebandwidth are divided in frequency into a plurality of orthogonalsubcarriers and data is transmitted in parallel on a plurality oforthogonal subcarriers, where bandwidths between 1.25 MHZ and 20 MHzbandwidth may the divided into 128 to 2048 orthogonal subcarriers forexample. Each subcarrier bandwidth may take any value but in LTE it isfixed at 15 KHz. As shown in FIG. 2, the resources of the wirelessaccess interface are also temporally divided into frames where a frame200 lasts 10 ms and is subdivided into 10 subframes 201 each with aduration of 1 ms. Each subframe is formed from 14 OFDM symbols and isdivided into two slots each of which comprise six or seven OFDM symbolsdepending on whether a normal or extended cyclic prefix is beingutilised between OFDM symbols for the redaction of intersymbolinterference. The resources within a slot may be divided into resourcesblocks 203 each comprising 12 subcarriers for the duration of one slotand the resources blocks further divided into resource elements 204which span one subcarrier for one OFDM symbol, where each rectangle 204represents a resource element.

In the simplified structure of the downlink of an LTE wireless accessinterface of FIG. 2, each subframe 201 comprises a control region 205for the transmission of control data, a data region 206 for thetransmission of user data, reference signals 207 and synchronisationsignals which are interspersed in the control and data regions inaccordance with a predetermined pattern. The control region 204 maycontain a number of physical channels for the transmission of controldata, such as a physical downlink control channel (PDCCH), a physicalcontrol format indicator channel (PCFICH) and a physical HARQ indicatorchannel (PHICH). The data region may contain a number of physicalchannel for the transmission of data, such as a physical downlink sharedchannel (PDSCH) and a physical broadcast channels (PBCH). Although thesephysical channels provide a wide range of functionality to LTE systems,in terms of resource allocation and the present disclosure PDCCH andPDSCH are most relevant. Further information on the structure andfunctioning of the physical channels of LTE systems can be found in[11].

Resources within the PDSCH may be allocated by an eNodeB to UEs beingserved by the eNodeB. For example, a number of resource blocks of thePDSCH may be allocated to a UE in order that it may receive data that ithas previously requested or data which is being pushed to it by theeNodeB, such as radio resource control (RRC) signalling. In FIG. 2, UE1has been allocated resources 208 of the data region 206, UE2 resources209 and UE resources 210. UEs in an LTE system may be allocated afraction of the available resources of the PDSCH and therefore UEs arerequired to be informed of the location, of their allocated resourceswithin the PBCSH so that only relevant data within the PDSCH is detectedand estimated. In order to inform the UEs of the location of theirallocated communications resources, resource control information,specifying downlink resource allocations is conveyed across the PDCCH ina form termed downlink control information (DCI), where resourceallocations for a PDSCH are communicated in a preceding PDCCH instancein the same subframe. During a resource allocation procedure, UEs thusmonitor the PDCCH for DCI addressed to them and once such a DCI isdetected, receive the DCI and detect and estimate the data from therelevant part of the PDSCH.

FIG. 3 provides a simplified schematic diagram of the structure of anuplink of an LIE wireless access interface that may be provided by or isassociation with the eNodeB of FIG. 1. In LTE networks the uplinkwireless access interface is based upon a single carrier frequencydivision multiplexing FDM (SC-FDM) interface and downlink and uplinkwireless access interfaces may be provided by frequency divisionduplexing (FDD) or time division duplexing (TDD), where in TDDimplementations subframes switch between uplink and downlink subframesin accordance with predefined patterns. However, regardless of the formof duplexing used, a common uplink frame structure is utilised. Thesimplified structure of FIG. 3 illustrates such an uplink frame in anPDD implementation. A frame 300 is divided in to 10 subframes 301 of 1ms duration where each subframe 381 comprises two slots 302 of 0.5 msduration. Each slot is then formed from seven OFDM symbols 303 where acyclic prefix 304 is inserted between each symbol in a manner equivalentto that in downlink subframes. In FIG. 3 a normal cyclic prefix is usedand therefore there are seven OFDM symbols within a subframe, however,if an extended cyclic prefix were to be used, each slot would containonly six OFDM symbols. The resources of the uplink subframes are alsodivided into resource blocks and resource elements in a similar manneris downlink subframes.

Each uplink subframe may include a plurality of different channels, forexample a physical uplink shared channel (PUSCH) 305, a physical uplinkcontrol channel (PUCCH) 306, and a physical random access channel(PRACH). The physical Uplink Control Channel (PUCCH) may carry controlinformation such as ACK/NACK to the eNodeB for downlink transmissions,scheduling request indicators (SRI) for UEs wishing to be scheduleduplink resources, and feedback of downlink channel state information(CSI) for example. The PUSCH may carry UE uplink data or some uplinkcontrol data. Resources of the PUSCH are granted via PDCCH, such a grantbeing typically triggered by communicating to the network the amount ofdata ready to be transmitted in a buffer at the UE. The PRACH may bescheduled in any of the resources of as uplink frame in accordance witha one of a plurality of PRACH patterns that may be signalled to UE indownlink signalling such as system information blocks. As well asphysical uplink channels, uplink subframes may also include referencesignals. For example, demodulation reference signals (DMRS) 307 andsounding reference signals (SRS) 308 may be present in an uplinksubframe where the DMRS occupy the fourth symbol of a slot in whichPUSCH is transmitted and are used for decoding of PUCCH and PUSCH data,and where SRS are used for uplink channel estimation at the eNodeB.Further information on the structure and functioning of the physicalchannels of LTE systems can be found in [1].

In an analogous manner to the resources of the PDSCH, resources of thePDSCH are required to be scheduled or granted by the serving eNodeB andthus if data is to be transmitted by a UE, resources of the PUSCH arerepaired to be granted to the UE by the eNodeB. At a UE, PUSCH resourceallocation is achieved by the transmission of a scheduling request or abuffer status report to its serving eNodeB. The scheduling request maybe made, when there is insufficient uplink resource for the UE to send abuffer status report, via the transmission of Uplink Control Information(UCI) on the PUCCH when there is so existing PUSCH allocation for theUE, or by transmission directly on the PUSCH when there is an existingPUSCH allocation for the UE. In response to a scheduling request, theeNodeB is configured to allocate a portion of the PUSCH resource to therequesting UE sufficient for transferring a buffer status report andthen inform the UE of the buffer status report resource allocation via aDCI is the PDCCH. Once or if the UE has PUSCH resource adequate to senda buffer state report, the buffer status report is sent to the eNodeBand gives the eNodeB information regarding the amount of data in anuplink buffer or buffers at the UE. After receiving the buffer statusreport, the eNodeB can allocate a portion of the PUSCH resources to thesending UE in order to transmit some of its buffered uplink data andthen inform the UE of the resource allocation via a DCI in the PDCCH.For example, presuming a UE has a connection with the eNodeB, the UEwill first transmit a PUSCH resource request in the PUCCH in the form ofa UCI. The UE will then monitor the PDCCH for an appropriate DCI,extract the details of the PUSCH resource allocation, and transmituplink data, at first comprising a buffer status report, and/or latercomprising a portion of the buffered data, in the allocated resources.

Although similar in structure to downlink subframes, uplink subframeshave a different control structure to downlink subframes, in particularthe upper 309 and lower 310 subcarriers/frequencies/resource blocks ofan uplink subframe are reserved for control signaling rather than theinitial symbols of a downlink subframe. Furthermore, although theresource allocation procedure for the downlink and uplink are relativelysimilar, the actual structure of the resources that may be allocated mayvary due to the different characteristics of the OFDM and SC-FDMinterfaces that are used in the downlink and uplink respectively, inOFDM each subcarrier is individually modulated and therefore it is notnecessary that frequency/subcarrier allocation are contiguous however,in SC-FDM subcarriers are modulation in combination and therefore ifefficient use of the available resources are to be made contiguousfrequency allocations for each UE are preferable.

As a result of the above described wireless interface structure andoperation, one or more UEs may communicate data to one another via acoordinating eNodeB, thus forming a conventional cellulartelecommunications system. Although cellular communications system suchas those based on the previously released LTE standards have beencommercially successful, a number of disadvantages are associated withsuch centralised systems. For example, if two UEs which are in closeproximity wish to communicate with each other, uplink and downlinkresources sufficient to convey the data are required. Consequently, twoportions of the system's resources are being used to convey a singleportion of data. A second disadvantage is that an eNodeB is required ifUEs, even when in close proximity, wish to communicate with one another.These limitations may be problematic when the system is experiencinghigh load or eNodeB coverage is not available, for instance in remoteareas or when eNodeBs are not functioning correctly. Overcoming theselimitations may increase both the capacity and efficiency of LTEnetworks but also lead to the creations of new revenue possibilities forLTE network operators.

Device-to-Device Communications

D2D communications offer the possibility to address the aforementionedproblems of network capacity and the requirement of network coverage forcommunications between LTE devices. For example, if user data can becommunicated directly between UEs only one set of resources is requiredto communicate the data rather than both uplink and downlink resources.Furthermore, if UEs are capable of communicating directly, UEs withinrange of each other may communicate even when outside of a coverage areaprovided an eNodeB. As a result of these potential benefits, theintroduction of D2D capabilities into LTE systems has been proposed.

FIG. 4 provides a schematic diagram of a mobile communications system400 that is substantially similar to that described with reference toFIG. 1 but where the UEs 401 402 403 are also operable to perform directdevice-to-device (D2D) communications with one another. D2Dcommunications comprise UEs directly communicating data between oneanother without user and or control data being communicated via adedicated coordinating entity such as an eNodeB. For example, in FIG. 4communications between the UEs 401 402 403 415 and the eNodeB 404 are inaccordance with the existing LTE standard, but as well as communicatingvia the uplink and downlinks 405 to 410, when the UEs 401 to 403 arewithin range of each other they may also communicate directly with oneanother via the D2D communication links 411 to 414. In FIG. 4 D2Dcommunications links are indicated by dashed lines and are shown toexist between 401 and 402, and 402 and 403 but not between 401 and 403because these UEs are not sufficiently close together to directlytransmit and receive signals to and from one another. D2D communicationslinks are also shown not to exist between 415 and other UEs because UE415 is not capable of D2D communications. A situation such as thatillustrated in FIG. 4 may exist in an LTE network where UE 415 is adevice not compliant with the specifications for D2D operation.

In order to establish a D2D communications link, such a one-way D2Dcommunications link 414 from the UE 402 to the UE 403, a number of stepsare required to be performed. Firstly, it is beneficial for theinitiating UE to have knowledge of the other D2D capable UEs withinrange. In an LTE system this may be achieved for example by each UEperiodically transmitting a discovery signal containing a unique“discovery” identifier that identifies UEs to one another.Alternatively, a serving eNodeB or coordinating entity may compile alist of UEs within its coverage area capable of performing D2Dcommunications and distribute the list to the appropriate UEs within itscoverage area. By virtue of either of the above processes the UE 401 maydiscover UE 402, UE 402 may discover UEs 401 and 403, and UE 403 maydiscover UE 402. Once UE 402 is aware of the existence of UE 403 it maythen proceed to establishing a D2D communications link with UE 403.

Previously Proposed D2D Systems

It has previously bees proposed to provide some arrangement for deviceto device communication within standards which define communicationssystems according to specifications administered by the 3GPP referred toas Long Term Evolution (LTE). A number of possible approaches to theimplementation of LTE D2D communications exist. For example, thewireless access interface provided for communications between UEs andeNodeB may be used for D2D communications, where an eNodeB allocates therequired resources and control signalling is communicated via the eNodeBbut user data is transmitted directly between UEs.

The wireless access interface utilised for D2D communications may beprovided in accordance with any of a number of techniques, such ascarrier sense multiple access (CSMA), OFDM or a combination thereof forexample as well as an OFDM/SC-FDMA 3GPP LTE based wireless accessinterface. For example it has bees proposed in document R2-133840 [1] touse a Carrier Sensed Multiple Access, CSMA, co-ordinations oftransmission by UEs, which is un-coordinated/contention based schedulingby each UE. Each UE first listens then transmits on an unused resource.

In another example, UEs may communicate with each other by negotiatingaccess to a wireless access interface directly, thus overcoming the needfor a coordinating eNodeB. Examples of previously proposed arrangementsinclude those in which one of the UEs of the group acts as a controllingentity to co-ordinate the transmissions of the other members of thegroup. Examples of such proposals are provided in the followingdisclosures:

-   -   [2]R2-133990, Network control for Public Safety D2D        Communications; Orange, Huawei, HiSilicon, Telecom Italia    -   [3] R2-134246, The Synchronizing Central Mode for Out of        Coverage D2D Communication; General Dynamics Broadband UK    -   [4] R2-134426, Medium Access for D2D communication; LG        Electronics Inc.

In another arrangement, one of the UEs of the group first sends ascheduling assignment, and then transmits data without a centralscheduling UE or controlling entity controlling the transmissions. Thefollowing disclosures provide, examples of this de-centralisedarrangement:

-   -   [5] R2-134238, D2D Scheduling Procedure; Ericsson;    -   [6] R2-134248, Possible mechanisms for resource selection in        connectionless D2D voice communication; General Dynamics        Broadband UK;    -   [7] R2-134431, Simulation results for D2D voice services using        connectionless approach; General Dynamics Broadband UK

In particular, the last two contributions listed above. R2-134248 [6],R2-134431 [7], disclose the use of a scheduling channel used by UEs toindicate their intention to schedule data along with the resources thatwill be used. The other disclosure, R2-134238 [5], does not use ascheduling channel as such, but deploys at least some predefinedresources to send the scheduling assignments.

Other example arrangements disclosed is [8] and [9] require a basestation to provide feedback to the communications devices to controltheir transmissions. Document [10] discloses an arrangement in which adedicated resource exchanging channel is provided between cellular userequipment and device-to-device user equipment for interference controland resource coordination.

As a result of the possible approaches to the organisation of a D2Ddevices and networks, a number of scenarios may arise. A selection ofexample scenarios are provided by FIGS. 5a to 5d where each may causedifferent problems regarding the allocation of resources, the operationof D2D communications alongside conventional LTE communication and themovement of D2D capable devices between coverage areas provided byeNodeBs.

In FIG. 5a UEs 501 and 582 are outside of a coverage area of an eNodeB,consequently, the D2D devices may communicate with little or no regardfor interference that may be caused by their D2D communications toneighbouring LTE networks. Such a scenario may occur in public safetycommunications for example, where either the UEs are outside of acoverage area or where the relevant mobile communications network is notcurrently functioning correctly. In such a scenario the communicatingUEs may either negotiate directly with one another to allocate resourcesand coordinate communications, or one of the UEs or a third UE may actas a coordinating entity and therefore perform resource allocation.

In FIG. 5b UE 501 is within a coverage area 504 of an eNodeB 503 and isperforming D2D communications with UE 502 which is outside the coveragearea 503. In contrast to the scenario of FIG. 5a , by virtue of UE 501being within the coverage area of the eNodeB 583, D2D communications maycause interference to conventional LTE communications within thecoverage area. Consequently, D2D resource allocations and transmissionsmay have to be coordinated around those within the coverage area 504 soconventional LTE communications are unaffected by D2D transmissions.This may be achieved in a number of ways, for example the eNodeB maycoordinate the resource allocation for the D2D communications so thatD2D resources and conventional LTE resources do not overlap. Anyallocations may then be relayed to UE 502 by UE 501. Alternatively, UE 1or UE2 via UE1 may for example perform resource allocation and theninform the eNodeB of the resources being utilised for D2Dcommunications. The eNodeB will then reserve these resources for D2Dcommunications.

In FIG. 5c both UE 501 and 502 are within the coverage area of theeNodeB 503, consequently, coordination between the eNodeB and UEs willbe required if D2D communications are to be performed without causinginterference to conventional LTE communications within the coveragearea. Such coordination may be achieved in a similar way to thatdescribed with reference to FIG. 5b but in the case of FIG. 5c UE 502 isalso within the coverage area and therefore the relaying of resourceallocation signals by UE1 to the eNodeB from UE 2 may not be required.

In FIG. 5d a fourth more complex D2D scenario is illustrated, where UE501 and UE 502 are each within the coverage areas 504 505 of differenteNodeBs 503 and 504 respectively. As for the scenarios of FIGS. 5b and5c , coordination, between the UEs performing D2D communications will berequired if interference between D2D communications and conventional LTEcommunications is to be avoided. However, the presence of two eNodeBsrequires that resource allocations by the eNodeBs within the coverageareas 504 and 505 are required to be coordinated around the D2Dresources allocations.

FIGS. 5a to 5d illustrates just four of a large number of possible D2Dusage, scenarios, where further scenarios may be formed fromcombinations of those illustrated in FIG. 5a to 5d . For example, twoUEs communicating as shown in FIG. 5a may move into the usage scenarioof FIG. 5d such that there are two groups of UEs performing D2Dcommunications in the coverage areas of two eNodeBs.

Once a D2D communications link is established, resources of the wirelessaccess interface are required to be allocated to the D2D link. Asdescribed above it is likely that D2D communication will take place inspectrum allocated for LTE networks, consequently it has been previouslyproposed that when within a coverage area of an LTE network, D2Dtransmission are performed in the uplink spectrum and that SC-FDM isused. Furthermore, as one of the motivating factors behind D2Dcommunication is the increase in capacity that may result, utilising thedownlink spectrum for D2D communications is not appropriate.

Co-pending EP patent application EP14153512.0 discloses an arrangementin which communications devices which are configured to perform D2Dcommunications, the contents of which are incorporated herein byreference. The communications devices are arranged to reserve sharedcommunications resources, such as those of the PUSCH of an LTE Up-link,by transmitting a scheduling assignment messages in a predeterminedsection of resources, referred to as a scheduling assignment region,allocated for performing contentious access. As disclosed isEP14153530.2, the contents of which are incorporated herein byreference, a contention resolution procedure is adopted by thecommunications devices so that if one or more communications devicestransmit scheduling assignment messages contemporaneously in the samesection of the scheduling assignment region then the communicationsdevices can detect the contentious access and re-try at a differenttime. The operation of communications devices can according to this D2Dcommunications procedure access is summarised in Annex 1 forcompleteness.

Operating Modes for Device-to-Device Communications

As explained above with reference to the different scenarios depicted inFIG. 5a-5d , communications devices or UEs may perform D2Dcommunications in different environments, depending on whether the UEsare within a coverage area provided by the eNodeBs of a mobilecommunications network or not. According to the present disclosure thescenarios mentioned above are summarised as being either within coverageand for which allocation of D2D communications resources is controlledby the eNodeB, which is referred to in the following description as mode1, or acting autonomously whether in coverage or out of coverage of aneNodeB, which is referred to as mode 2, in which communicationsresources are accessed by the D2D UEs autonomously without beingallocated by the eNodeB. These two modes of operation are presented inFIGS. 6 and 8, with a supporting explanation of an application of D2Dcommunications which is a press to talk type operation between a groupof D2D UEs.

FIG. 6 provides an example illustration of communications devices 600which are operating within a coverage area represented by a dashedboundary line 601 provided by a base station or eNodeB 602. When D2Dcommunications is performed within a coverage area provided by a mobilecommunications network then communications resources of a wirelessaccess interface are provided under the control of the mobilecommunications network.

As shown in FIG. 6, each of the communications devices or UE's 600includes a transmitter 606 and a receiver 608 which perform thetransmission and reception of signals under the control of thecontroller 610. The controller 610 controls the transmitter 606 and thereceiver 608 to transmit and receive data, between members of the groupto perform D2D communications. However, as will be appreciated in thismode of operation, which is referred to as mode 1 operation access tothe wireless access interface is determined and controlled by the eNodeB602.

According to this example of the mode 1 operation, a procedure forperforming D2D communications according to a press to talk typeapplication for D2D communications is shown in FIG. 7, which is based ina disclosure provided in reference [5]. FIG. 7 provides a messagesequence flow diagram illustrating a process in which a UE performs D2Dcommunications within the coverage area 601 of an eNodeB 602 andtherefore requests and receives allocations of communications resourcesfrom the eNodeB 602. As shown in FIG. 7 as a first part of the processthe UEs 606 are arranged to be preconfigured for being allocating andaccessing communications resources by being provided with encryptionkeys and authentication in a step 701. In step 702 a firstcommunications device 701 wishes to transmit to other UEs is the groupsuch as a UE 706 and to perform a press to talk activity as representedby a process step 708. According to one of the arrangements representedabove the UE 794 then requests communications resources of a wirelessaccess interface provided by the eNodeB 602 and receives a grant ofcommunications resources of the wireless access interface from theeNodeB as represented in a process step 710. The first UE 704 thentransmits a scheduling assignment message to the other UE in the group706 using a message 712 and then transmits user data to the other UEs inthe group on the steps 714, 716. A further scheduling assignment messagemay be sent 718 to continue to transmit user data to the other UEs 728.Thus the messages 712 to 720 represent the transmission session 722 fortransmitting data to the other UEs. A further request for communicationsresources may be made in a step 730 to the other UEs to renew or receivea greater amount of communications resource from the eNodeB 602 asperformed by a process step 730. A further scheduling assignment message732 and user data transmission is performed in a further transmissionsession 736. Finally the UE 704 releases the press to talk request in astep 740 to release the communications resource, which have beenallocated by the eNodeB 602 for the transmission for D2D communications.

A further example mode of operation as explained above is referred to asa mode 2 in which D2D communications are performed in an out of coveragemode in which the communications devices or UEs are outside a coveragearea 601 of the base station 602 as represented in FIG. 8 whichcorresponds substantially to the example showing in FIG. 6 whichcorresponds to an in coverage operation of mode 1. Thus as tea in FIG. 8the UE's 600 are outside the boundary 601 and therefore are outside acoverage area provided by the eNodeB 602. Whether or not the UE 610 iswithin a coverage area of the eNodeB 602, can be determined inaccordance with predetermined conditions such as a downlink receivedsignal strength indication which for example may be below apredetermined threshold. Thus the transmitter, the receiver and thecontroller 606, 608, 609 may determine in accordance with the receivedsignal strength that the downlink transmissions from eNodeB are below apredetermined threshold and therefore conclude that the UE is operatingoutside a coverage area provided by the eNodeB 602. Accordingly, for thepress to talk example as shown in FIG. 7, a message flow diagramcorresponding to a press to talk operation in the mode 2 operation thatis shown in FIG. 9. FIG. 9 is explained as follows:

As shown in FIG. 9, during a first process step, corresponding to step701 in FIG. 7, the UEs perform, a pre-configuration in whichauthentication and encryption keys are exchanged or provided by acommunications network in order that the UEs can communicate via thewireless access interface. Thus in the first step resource configurationis performed 901. A first UE 902 then performs a press to talk activityas represented by a press to talk activated step 904. In a process stepshown generally as a D2D communications procedure the first UE 902performs a procedure to reserve communications resources of the wirelessaccess interface in order to form a D2D communication to the second UE908. The second UE 908 may be one device although there are otherdevices of the group available who may receive the communication fromthe first device 902. Having reserved the communications resources onthe wireless access interface the first UE 902 then transmits user dateto the other devices in the group 908 as represented by messagetransmission arrows 912, 914, 916. Accordingly, the transmissionmessages 912, 914, 916 are represented generally as a transmissionsession 918.

In a further operation, the first UE 902 may perform a further D2Dcommunications procedure to reserve communications resources of awireless access interface 920 which may be required in order to renewthe reservation or to reserve further resources as required. According,further transmissions occur 922, 924 in a further communications session926. Finally after press to talk function is released in a step 930 sothat the reserved resources are released by the UE 902.

According to the agreements above, the UE should use mode 1 whenin-coverage of the network. For mode 1 operation, the UE has to be RRCConnected before mode 1 can operate. As will be appreciated there aresome advantages for arranging that whenever the UE is in-coverage(according to the current definition: the cell being suitable) then theUE should establish an RRC Connection with the network and then thenetwork schedules specific resources for the UE.

According to some examples, the mobile communications network cancontrol whether mode 1 or mode 2 can be allowed. For example enablingmode 1 or 2 via system information, for example 1 bit indication for

-   -   Mode 2 allowed in-coverage and/or out-of-coverage    -   Mode 1 required (mode 2 not allowed) or mode 2 allowed        in-coverage.

A problem can be perceived if a UE is required to operate in mode 1,because the UE would have to establish and as RRC connection from idlemode. As such, a UE, which is in a suitable cell, in idle mode, willdelay any public safety or any other D2D communication by an amount oftime which it takes to establish an RRC connection and request D2Dresources, and an eNodeB to allocate the resources. Under normaloperating conditions a delay for communications earned by the UE havingto move from idle to RRC connected state, would be a few hundredmilliseconds, which does not represent a significant delay toestablishing communications. However in some situations, particularly ina congested network, this delay may be unacceptable, or may even preventa public safety device from being able to operate.

One example is that in case of a disaster, such as earthquake, bombing,or any situation, which respires D2D communications devices operated byemergency services to function, provide examples in which a mobilecommunications network may become congested because many people mayattempt to call, or test friends and relatives. This can causecongestion on PRACH and as a result the network may not be able to serveall UEs. This PRACH failure could also be earned by temporaryinterference, or even core network or an eNodeB failure.

In a prior art document EP 0993314 [15] discloses an arrangement in aCDMA wireless access interface in which radio access channel resourcesprovided by the wireless access interface are divided between differenttypes of access as a priority basis. Higher priority access typesreceive more physical resources for random access. This arrangementprovides an improvement in a possibility of gaining access to thenetwork due to the higher probability that a particular message will besuccessful in a contentious access. Therefore, more important UE classescan have a higher probability of a successful contentious access.

For an example in which a mobile communications network becomescongested, the network could be arranged to set access class barring toprevent normal users from accessing a cell. Assuming that a publicsafety device will have a special access class (access classes 11-15reserved for special devices) then these devices may be able to accessthe cell. However, updating access class barring parameters may takesome time. Furthermore there are some network failure scenarios, whichcould prevent the communication of system information. In addition, evenif the UE is able to establish a connect then the resource allocationmay be unreliable in volatile circumstances.

Access Control for D2D Communications

The embodiments of the present technique can provide an arrangement forrestricting or controlling communications devices, which are performingD2D communications. The control may be initiated for example as a resultof an emergency situation so that a priority can be given to UEsperforming D2D communications for supporting emergency services forexample. In other examples access may be restricted to D2Dcommunications resources in order to manage congestion for accessing theD2D communications resources. Embodiments of the present technique canprovide an arrangement for supporting different types or classes of UEswhich are performing D2D communications. However, in order to supporthigher priority UEs such as public safety devices, in high loadscenarios and/or high interference scenarios it may be necessary toprovide some discrimination in the access to D2D communicationsresources. Far a cellular network, it is possible to control the load bybarring different classes of UE (access class barring) or providing aprobability of access.

Embodiments of the preset technique can provide one or more sections orpools of communications resources, each pool of resources and/orresource allocation mode being associated with additional parametersspecifying which types of UE are allowed to access those communicationsresources, associating barring information/access rights with D2Dcommunications resource pools and/or modes of communication.

As will be appreciated from the explanation provided above, D2Dcommunications resources can be viewed as comprising at least threetypes, which are:

1) Out of coverage resource pool

-   -   These resources are used by a transmitting UE which is not in        the coverage of an eNodeB.    -   This type of operation is intended only for the public safety        UEs.

2) Edge-of-coverage resources/mode 2 in-coverage pool

-   -   This is a mode of operation whereby the UE selects resources        autonomously from a pool of resources broadcast by the eNodeB to        a UE which is in a coverage area for radio communications with        the eNodeB of.    -   UE either does not have an RRC Connection to perform mode 1, or        the network has configured that the UE will use mode 2 instead        of mode 1.    -   This may be applicable for commercial D2D devices as well as        public safety devices

3) in-coverage scheduled resource pool/mode 1

-   -   The eNodeB schedules specific resources to the transmitting D2D        UE while UE has RRC Connection to the cellular network.    -   This may be applicable for commercial D2D devices as well as        public safety devices

For at least the examples according to communications resource pools oftypes (2) and (3), it is possible that many UEs in the cell may camecongestion. In particular in mode 2, this could prevent public safetyUEs from gaining access to a communications resource if a singleresource pool is provided for all UEs. It is also possible that mode 1can be congested.

Embodiments of the present technique can provide an arrangement in whichfor each of a plurality of communications resources pools, an indicationis provided to each of a plurality of different types or classes of UEsas to whether or not UEs of that type are allowed access to thecommunications resources of the pool.

This might be done by a single indication, which informs the UE that theresource pool is for public safety only, commercial UE only, or alltypes of UE. In one example the mobile communications network canprovide a plurality of different resource pools for use for example byUEs operating in mode 2 for D2D communications. A public safety devicemay use the resource pool indicated for use in public safety, and acommercial device may use another resource pool, so that some resourcesare specifically assigned for public safety, presenting commercial UEsfrom taking those resources.

For example, UEs which are configured to operate in mode 2 could besignaled along with an associated mode 1 communications resource pool,to apply only to public safety devices, while mode 1 may the specificfor commercial devices or all devices. In this case it would be mode 2operation and the associate communications resource pool that wasrestricted to public safety devices.

An example embodiment of the present technique is showing in FIG. 10. InFIG. 10 an eNodeB 960 is shown to comprise a transmitter 962, a receiver964 and a controller 966. Also shown in FIG. 10 a plurality of UEs 970each include a transmitter 972, a receiver 974 and a controller 976. Thecontroller controls the transmitter and the receiver 972, 974 in orderto transmit and receive data via the eNodeB 960 or to perform D2Dcommunications as explained above. As shown in FIG. 10, two groups 978,980 three UE's 970.1, 970.2 are each performing D2D communications witheach other using different communications resources. A first group ofUEs 978 perform D2D communications using mode 1 operation using firstcommunications resources represented a block 986. The second group ofUE's 980 performs D2D communications is accordance with mode 2 operationusing a second group of communications resources represented by a box912. The second communications resources 982 may for example be reservedfor supporting D2D communications at the edge or within a certain partof a coverage area represented by a broken 992.

As explained above, the UE's 970 can perform D2D communications usingmode 1 in which access to the first communications resources 986 iscontrolled by the eNodeB 968 in which the UE's request and are grantedone or more resources from within the first communications resources 986to perform D2D communications to the other UEs within the group. OtherUEs may operate in mode 2 in which D2D communications are performed inaccordance with a D2D communications protocol using the secondcommunications resources 982. Therefore, for example the second group ofUE's 980 may perform contentious access for the second communicationsresources 982.

As explained above, according to the present technique the eNodeB 960transmits to the UE's 970 an indication as to whether or nor they canuse either the first communications resources 986 or the secondcommunications resources 982 or both.

In some examples, this access to the first and second communicationsresources 982,986 would depend on a class of the communications devices.As explained above, communications devices, which provide apress-to-talk application used by the emergency services may be in adifferent class and therefore have a higher priority than commercialUEs. Accordingly, the commercial UEs may be restricted to using thefirst communications resources 986 in mode 1 operation.

As shown by the message flow diagram shown in FIG. 11, access rights aregranted to UEs 1010 by an eNodeB 1012 by transmitting system informationperiodically to UEs which support communicating using D2Dcommunications. The system information is transmitted in a message 1014,which identifies resource pools associated with mode 2 operation that isthe second communications resources. In some examples, the secondcommunications resources may comprise two resource pools, one which isrestricted to public safety rules and the other which is restricted tocommercial rules. In a process step 1016 the UE 1010 is configured todetermine, based on the access rights information received in the systeminformation from the eNodeB the communications resource pools to whichthe UE is allowed access to select and therefore perform D2Dcommunications in accordance with mode 2 operation. Accordingly, afterselecting one of the resource, pools allocated to the UE in accordancewith its class, the UE transmits a D2D transmission to another UE 1020within its grasp as represented by a message transmission 1022.

The receiving UE also needs to know the resource pools, which it shouldmonitor, so the receiving UE can also use the barring information todetermine which communications resource pools may contain data which itshould receive (e.g., allowing UE to monitor only the public safetyresource pool or pools). If the receiving UE belongs to a class that istemporary barred from all D2D communication, then the UE can refrainfrom monitoring until next broadcast indicating that the UE is no longerbarred. A barring timer may be provided and used in a similar way to theexisting Tbarred used for cell barring.

For an example in which the network restricts the UEs operating toperform D2D communication in mode 1 operation, the UE can be arranged todetermine whether it is allowed to initiate RRC Connection establishmentto perform a mode 1 D2D communication.

Based on the access control check, the UE may determine which mode ofoperation the UE should use. For example a UE may perform an accesscontrol check on a mode 2 communications resource pool, which it fails(the probability check may fail) and as a result the UE selects mode 1and initiates an RRC Connection establishment procedure. This exampleoperation is presented in FIG. 12.

Another example would be that mode 2 operation is allowed, butrestricted to public safety devices. This means a commercial devicealways fails the mode 2 access rights check and has to be RRC Connectedto use mode 1 operation, whereas a public safety device may use mode 2(potentially based on other additional criteria also such as a receivedDL power threshold)

An example in which access rights are communicated to UE's performingD2D communications is shown in FIG. 12. In FIG. 12 a UE 1110 receivessystem information from an eNodeB 1112 indicating access rights of theUE for mode 1 operation. Thus periodically the eNodeB 1112 transmitssystem information to, for example, the first group of UE's shown inFIG. 10 which are accessing the first communications resources usingmode 1 operation. In a process step 1114, the UE 1110 is configured todetermine, based on the system information indicating whether it isallowed to access the fast communications resources whether the systeminformation it has received determines whether it is allowed to triggeran RRC connection establishment to perform mode 1 D2D communicationsusing the first communications resources. Accordingly, if the UE 1110 isallowed access to the first communications resources to operate in mode1 then the UE performs an RRC connection establishment procedure asrepresented by a double heading arrow 1116 in which it initiates a RRCconnection establishment required for mode 1 operation provided it hasthe access rights to do so. Accordingly, after establishing an RRCconnection then the UE 1110 can transmit a D2D communication to anotherUE within the group 1118 as represented by a message arrow 1120.

The operation of an eNodeB according to the present technique issummarised by the flow diagram shown in FIG. 13, which is explained asfollows:

S1201: The eNodeB is provided with a transmitter, a receiver and acontroller as explained above with reference to FIG. 10. The controllercontrols the formation of the wireless access interface by schedulingand allocating resources for transmission and reception by the UEs. Thecontroller configures a first selection of communications resources ofthe wireless access interface as shown in FIG. 10 which can be allocatedon request to communications devices via the controller for D2Dcommunications in accordance with mode 1 operation.

S1202: The controller also in the present example configures secondcommunications resources of the wireless access interface, which can beused for D2D communications in accordance with mode 2 operation using aD2D communications protocol. As explained above an example of a D2Dcommunications protocol is provided in annex 1 which performs schedulingassignment transmission in accordance with a contentious accessprocedure for a resource from the second communications resources pool.Accordingly, the UEs access the second communications resources withoutreference to the eNodeB and therefore act autonomously.

S1204: The controller then identifies a class of each of thecommunications devices which is to perform D2D communications.

S1206: The controller of the eNodeB determines, depending on the classof each of the communications device, which is to perform D2Dcommunications whether the UE can have access to one or more of thefirst communications resources or the wireless access interface or thesecond communications resources of the wireless access interface orboth. Thus the controller may determine that a UE can only have accessto the first communications resources in accordance with its class.Alternatively, an emergency services UE may be granted access to thesecond communications resources to perform D2D communications using mode2.

S1208: The controller of the eNodeB generates for each of the one ormore communications devices an indication as to whether or not the UE isallowed access to either the first communications resources of thewireless access interface or the second communications resources of thewireless access interface or both the first and the secondcommunications resources depending on the class of the communicationsdevice.

S1210: The controller then controls the transmitter to transmit via thewireless access interface, via for example system information messagesto each of the one or more UEs. The generated indication as to whetheror not the UE can access the first or second communications resources orboth the fast and second communications resources will depend on theirclass.

In some example embodiments in addition to the process performed by theeNodeB in the flow diagram showing in FIG. 13 the eNodeB may change theaccess rights granted to particular classes of UE's independence uponpredetermined conditions. The predetermined conditions may be that themobile network operator is provided with an indication that an emergencyhas occurred and therefore changes the access rights to differentclasses of UEs for example giving greater access rights to emergencyservices UEs. In other examples the eNodeB or other parts of the mobilecommunications network may detect that congestion is present on thenetwork and therefore may control access to the D2D communications andtherefore wish to change the access allowed by the UEs to either thefirst and/or the second communications resources. FIG. 14 is summarisedas follows:

S1301: In a first step the controller in the eNodeB determines whetherthe conditions for network access has changed.

S1302: The controller of the eNodeB then determines whether to changethe configuration of the first or second communications resources. Forexample the eNodeB may determine that it wishes to change the relativeproportion of communications resources allocated to the firstcommunications resources compared to those of the second communicationsresources. If the answer is no then processing may move to step S1310.

S1304: If the controller of the eNodeB decides that it is appropriate tore-configure the first communications resources and/or the secondcommunications resources then an adjustment is made in the relativeproportion of these resources with respect to each other.

S1306: The controller then generates information identifying the changeof the first and second communications resources.

S1308: The controller then transmits to the UE's performing D2Dcommunications the information identifying the changed fast and/orsecond communications resources.

S1310: The controller then determines whether it is appropriate tochange the access rights of UEs which may for example be dependent onthe class of the UE and therefore may the different depending on theclass of UE.

S1312: The controller of the eNodeB then determines depending on theclass of each of the communications devices a change of whether the UEcan have access to one or more of the first communications resources orthe second communications resources of the wireless access interface.

S1314: The controller then regenerates, for each of the one or more UEs,the changed indication of whether the UE's can have access to either thefirst communications resources or the second communications resources orboth, the first and the second communication resources depending on theclass of the UE.

S1316: The controller then uses the transmitter to transmit the changein indication of access rights to the first and/or second communicationsresources using for example the system information transmission.

S1318: Processing then loops back to a wait state S1318 beforeproceeding again to determine whether conditions for network access havechanged. As will be appreciated, changes can be communicatedindependently or together at the same time (see FIG. 14).

The operation of the UE in configuring its D2D communications inaccordance with its access rights to communications resource pools issummarised in FIG. 15. FIG. 15 is explained as follows:

S1401: The UE my be preconfigured or may receive an indication from themobile communications network of a configuration of first communicationsresources of the wireless access interface, which can be used by the UEto request communications resources from the eNodeB to perform D2Dcommunications in accordance with mode 1 operation.

S1402: The UE may also be preconfigured or may receive as indicationfrom the eNodeB of second communications resources of a wireless accessinterface, which can be used for D2D communications in accordance withmode 2 operation. As explained above in mode 2 operation the UE requiresthe use of a D2D communications protocol for example using contentionaccess.

S1404: The UE receives from the eNodeB an indication of whether the UEcan use either the first communications resources of the wireless accessinterface for performing D2D communications in accordance with mode 1operation or the second communications resources of the wireless accessinterface for performing D2D communications in accordance with mode 2operation or access to both first and second communications resources.

S1406: The UE then determines whether it is allowed access to the firstcommunications resources depending on its class then processing proceedsto step S1406 in which D2D communications are performed using the firstcommunications resources by requesting and being granted access to thefirst communications resources via the eNodeB in accordance with mode 1operation. In parallel or alternatively, the UE may determine whether itcan use the second communications resources using mode 2 operation.Accordingly, in the step S1412 the UE performs D2D communications usingthe second communications resources in mode 2 using a D2D communicationsprotocol for example by using contentious access.

Further Aspects

Is some example embodiments the mobile communications network may beconfigured to combine the indication provide to the UEs to controlaccess to the communications resources in accordance with their classwith access class barring and associate either the existing cell barringparameters, or signal additional D2D specific parameters.

Currently in LTE access classes 0-9 are categories which provide apriority class to “normal” devices. Access class 10 is for emergencycalls. Access classes 11-15 are high priority classes. Public safetyclasses would typically be access class 12, 13, 14.

Access classes 8-9 can be provided with a probability of access beforeaccessing the cell, the UE applies a randomly chosen valise against athreshold (representing the probability). The UE cannot access the cellif this check does not pass. Other access classes can be individuallybarred or allowed. Accordingly, each of the access class can be providedwith an additional indication as to whether the UE performing D2Dcommunications can have access to a communications resource poolaccording to its class and combine this with the probability of accessand access waiting time to perform access control in a more graduatedmanner. For example 1 bit indicating access classes. 0-9 are allowed,and individual bits for at least classes 12, 13, 14.

Various further aspects and features of the present invention aredefined in the appended claims. Embodiments of the present techniquefind application with any communications device, which may perform D2Dcommunications for any scenario.

In some embodiments of the present technique the access control providedby the indicated access rights transmitted to UEs could be used by areceiving UE to determine which resources it should monitor in order toreceive D2D transmissions. Accordingly, if the UE does not have accessrights to a pool of communications resources allocated for D2Dcommunications then a power saving can be achieved.

Annex 1: Example of Autonomous D2D Communications

An arrangement is which D2D communications can be performed between oneor more UEs, which may form a group of UEs, without requiring a centralentity to control the transmission of signals from the UEs to the otherUEs of the group is briefly described, with reference to FIG. 16.According to this arrangement, a wireless access interface is providedwhich includes a scheduling assignment region or channel in whichscheduling assignment messages may be transmitted in a plurality ofsections of communications resources. Each of the plurality ofcommunications resource has a corresponding section of resources of ashared communications channel. The transmission of a schedulingassignment message in one of the sections of the scheduling assignmentregion can provide an indication to all of the other devices in a groupthat a UE wishes to transmit signals representing data in acorresponding section of the shared communications resources.

In FIG. 16, the wireless access interface is formed from a plurality ofOFDM sub carriers 1501 and a plurality of OFDM symbols 1502 which can bedivided into sections of communications resources. As shown in FIG. 16,the wireless access interface is divided into time divided units ofsubframes 1504, 1506, 1508, 1510 of communications resource. As shown inFIG. 16, every other subframe includes a scheduling assignment region1512, 1514. The scheduling assignment region includes a plurality ofsections of communications resource which are numbered in FIG. 16 from 1to 84. A remaining part of the subframes 1504, 1508 in which ascheduling assignment region 1512, 1514 is included is divided into aplurality of sections of shared communications resources. Othersubframes in which there is no scheduling assignment region 1512, 1514are divided into sections of shared communications resource for thetransmission of signals representing data by the UE to other UEs withinthe group. However, in combination a plurality of sections ofcommunications resources of shared resources are provided within twosubframes 1504, 1506, 1508, 1510 and each of the sections of sharedresource corresponds to one of the sections of the scheduling assignmentregion 1512, 1514. Accordingly, a transmission by a UE in one of thesections of the scheduling assignment region of a scheduling assignmentmessage indicates to the other UEs within the group that the UE whichtransmitted the scheduling assignment message in that section of thescheduling assignment region intends to transmit data in a correspondingsection of the shared communications resources in which data can betransmitted. Thus as represented by the arrow 1520, the transmission ofa scheduling assignment in section 81 of the scheduling assignmentregion 1512 provides an indication to the other UEs in the group thatthe transmitting UE that transmitted the scheduling assignment messageintends to transmit data in the section numbered 81 of the schedulingassignment resource.

FIG. 16 therefore shows a potential arrangement for implicit resourcescheduling. For the example shown in FIG. 16, the scheduling assignmentresource or region 1512 has been chosen to be one uplink resource blockof a conventional LTE wireless access interface, transmitted everysecond subframe.

In some examples, the scheduling assignment message may include one ormore identifiers which may include but are not limited to an identifierof the transmitting UE, an identifier of the destination device ordevices, a logical channel identifier, transport channel identifier, andapplication identifier, or an identifier of the group of UEs dependingupon the application. For example if the group of UEs were engaged in apush-to-talk communications session, then the scheduling assignmentmessage would not need to identify the individual device, but only thegroup of UEs. Other devices within the group, which detect thetransmission of the scheduling assignment message in a section of thescheduling assignment region will know not to attempt to transmit in thecorresponding section of the shared communications resources fortransmitting data and will detect the identifier of the group of UEs.The devices of the group will therefore know to listen and to receivethe data transmitted by the transmitting UEs (UE), which transmitted thescheduling assignment message, which included the group identifier.

As shown in FIG. 16 the resource numbered 81 corresponds to a region inthe next available communications resource for that number that is inthe third subframes 708. Thus there is a corresponding delay betweentransmission of the scheduling assignment message and the transmissionof the data in order to provide notice to the other UEs in the groupthat that particular section of the shared communications resources hasbeen reserved by one of the UEs for transmission.

In order resolve a contentious access a two phase contention resolutionprocess is proposed:

In a Phase 1: A fixed sequence of listening for resource reservations(and potentially listening also for on going data transmission or otherinformation such as measurements from other UEs) or optionally in someexample transmission of messages in a scheduling region.

If the UE detects the chosen resource is in use or being requested byanother UE, the UE randomly picks another resource from the sharedcommunications resources. The phase 1 may be repeated if thecommunications resources need to change.

This phase 1 solves collisions in most of the cases, with the exceptionbeing if two UE start listening at exactly the same subframe.

In Phase 2 the LIE transmits in the selected communications resources orin the case in which a scheduling channel is present, the UE transmits amessage to inform the other UEs that it intends to transmit in thecorresponding communications resources of the shared channel. After arandom time a further listening process is performed to determinewhether a collision has occurred because another UE is transmittingcontemporaneously.

The UE may restart one or both of the phases if collision is detected.

The UE may also perform random backoff time before restarting.

This phase 2 is intended to address the case in which two UEs start atexactly the same time, and contention is not detected in phase 1. Therandom listening slot reduces overall probability of collision, so thatthe larger the number of preamble frames the lower the probability ofcollision.

The network or a co-ordinating UE may configure the length of thepreamble phase based on e.g. number of devices in proximity.

In some example a counter may be incremented after each schedulingmessage transmission if this example embodiment is used. This can helpto determine which UE should choose another resource in case ofcollision, for example if a scheduling message from another UE isdefected with a higher counter, or if the UE detects another UE in phase2, then a different set of communications resources can be chosen.

After the UE transmits the signals representing the data then, the UEmay wait for a predetermined period or a random period before it makesan attempt to transmit further data to avoid collisions with other UEs.

According, to this arrangement a probability of collision betweendifferent transmitting UEs in proximity with one another is reducedcompared to simply listening before transmitting. Furthermore, arelatively short delay for collision detection (in order of a fewsubframes) can the achieved, and a configurable preamble length canprovide a facility for addressing different numbers of UEs in thesystem. For example a longer preamble length (the total number ofsubframes in phases 1 and 2) may be needed in case of high number of UEsto reduce collision probability.

Various further aspects and features of the present invention aredefined in the appended claims and various combinations of the featuresof the dependent claims may be made with those of the independent claimsother than the specific combinations recited for the claim dependency.Modifications may also be made to the embodiments hereinbefore describedwithout departing from the scope of the present invention. For instance,although a feature may appear to be described in connection withparticular embodiments, one skilled in the art would recognise thatvarious features of the described embodiments may be combined inaccordance with the disclosure.

In the foregoing description D2D communications are described withreference to an LTE system, however the presently disclosed techniquesare equally applicable to after LTE system structures and other systemswhich are compatible with D2D communications.

The following numbered paragraphs define further example aspects andfeatures of the present technique:

Paragraph 1. A method of communicating using a communications device viaa wireless access interface to perform device-to-device communications,the method comprising

configuring the communications device with at least one of

an indication of one or more first communications resources of thewireless access interface which can be allocated on request to thecommunications device by a mobile communications network fortransmitting signals to one or more other communications devices orreceiving signals from the one or more other communications devices inaccordance with the first mode of operation, when the communicationsdevice is within a coverage area provided by the mobile communicationsnetwork, and

an indication of one or more second communications resources of thewireless access interface which can be used by the communications devicefor transmitting signals to one or more other communications devices orreceiving signals from the one or more other communications devices inaccordance with a second mode of operation using a device to devicecommunications protocol, when the communications device is within thecoverage area provided by the mobile communications network, and

receiving, from the mobile communications network, an indication ofwhether the communications device can use at least one of the firstcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation or the second communications resources of the wireless accessinterface for performing device to device communications in accordancewith the second mode of operation, and

depending on the indication provided by the mobile communicationsnetwork and the configuration of the one or more of the firstcommunications resources,

transmitting signals to the one or more other communications devices viathe first communications resources allocated by the mobilecommunications network in accordance with a first mode of operation orreceiving signals from the one or more other communications devices viathe first communications resources, or

depending on the indication provided by the mobile communicationsnetwork and the configuration of the one or more of the secondcommunications resources, transmitting signals to the one or more othercommunications devices via the second communications resources orreceiving signals from the one or more other communications devices viathe second communications resources in accordance with the second modeof operation using the device to device communications protocol.

Paragraph 2. A method of communicating according to paragraph 1, whereinthe indication received by the communications device of whether thecommunications device can use at least one of the first communicationsresources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation or the second communications resources of the wireless accessinterface for performing device to device communications in accordancewith the second made of operation is dependent upon one of a pluralityof predetermined classes of communications devices.Paragraph 3. A method of communicating according to paragraph 1 or 2,comprising

configuring the communications device with one of a predeterminedplurality of classes, each of the predetermined classes indicating anaccess class, each, access class having associated therewith an accessprobability level and a wait time,

determining in accordance with the access probability whether thecommunications device can transmit signals via the first communicationsresources or the second communications resources depending on thereceived indication at a current time, and if the communications devicecannot transmit signals at the current time according to the accessprobability waiting for the wait time.

Paragraph 4. A method of communicating according to paragraph 1, 2 or 3,wherein the transmitting the signals, depending an the indicationprovided by the mobile communications network to the one or more othercommunications devices via the first communications resources allocatedby the mobile communications network in accordance with a first mode ofoperation or transmitting the signals to the one or more othercommunications devices via the second communications resources via thesecond communications resources in accordance with the second mode ofoperation using the device to device communications protocol includes

determining in accordance with predetermined conditions whether thecommunications device is within a coverage area for transmitting orreceiving radio signals via the wireless access interface provided by amobile communications network, and

if the communications device is determined to be within the coveragearea of the mobile communications network and has received theindication of communications resources for transmitting signals to oneor more other communications devices, when within a coverage area of themobile communications network, then

depending on the indication and the configuration of the one or more ofthe first communications resources, transmitting the signals to the oneor more other communications devices via the first communicationsresources allocated by the mobile communications network in accordancewith a first mode of operation, or

depending on the indication and the configuration of the one or more ofthe second communications resources, transmitting the signals to the oneor more other communications devices via the second communicationsresources via the second communications resources in accordance with thesecond mode of operation/using the device to device communicationsprotocol, or

if the communications device is determined not to be within the coveragearea of the mobile communications network,

transmitting signals via the wireless access interface to one or moreother communications devices in accordance with the device to devicecommunications by accessing the first or second communications resourcesor one or more other communications resources of the wireless access inaccordance with a second operating mode of a device to devicecommunications protocol.

Paragraph 5. A method according to any of paragraphs 1 to 4, wherein thetransmitting the signals to the one or more other communications devicesvia the second communications resources in accordance with the secondmode of operation using the device to device communications protocolincludes

performing a contentious access procedure for the second communicationsresources

Paragraph 6. A method of communicating according to any of paragraphs 1to 5, wherein first communications resources and the secondcommunications resources include one or more communications resourceswhich are the same.

Paragraph. 7. A method of communicating according to any of paragraphs 1to 6, comprising

receiving, periodically, from the mobile communications network,information identifying at least one of the first communicationsresources of the wireless access interface or the second communicationsresources of the wireless access interface.

Paragraph 8. A communications device comprising

a transmitter configured to transmit signals to one or more othercommunications devices via a wireless access interface to performdevice-to-device communications,

a receiver configured to receive signals from the one or more othercommunications devices via the wireless access interface, and

a controller for controlling the transmitter and the receiver totransmit or to receive the signals via the wireless access interface totransmit or to receive date represented by the signals in accordancewith a device to device communications, wherein the controller isprovided with at least one of

an indication of one or more first communications resources of thewireless access interface which can the allocated on request to thecommunications device by a mobile communications network fortransmitting signals to one or more other communications devices orreceiving signals from the one or more other communications devices inaccordance with the first mode of operation, when the communicationsdevice is within a coverage area provided by the mobile communicationsnetwork, and

an indication of one or more second communications resources of thewireless access interface which can be used by the communications devicefor transmitting signals to one or more other communications devices orreceiving signals from the one or more other communications devices inaccordance with a second mode of operation using device to devicecommunications protocol, when the communications device is within thecoverage area provided by the mobile communications network, and thecontroller is configured in combination with the transmitter and thereceiver

to receive, from the mobile communications network, an indication ofwhether the communications device can use at least one of the firstcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation or the second communications resources of the wireless accessinterface for performing device to device communications in accordancewith the second mode of operation, and

depending on the indication provided by the mobile communicationsnetwork and the configuration of the one or more of the firstcommunications resources,

to transmit signals to the one or more other communications devices viathe first communications resources allocated by the mobilecommunications network in accordance with a first mode of operation orreceiving signals from the one or more other communications devices viathe first communications resources, or

depending on the indication provided by the mobile communicationsnetwork and the configuration of the one or more of the secondcommunications resources, to transmit signals to the one or more, othercommunications devices via the second communications resources orreceiving signals from the one or more other communications devices viathe second communications resources in accordance with the second modeof operation using the device to device communications protocol.

Paragraph 9. A communications device according to paragraph 8, whereinthe indication received by the communications device of whether thecommunications device can use at least one of

the first communications resources of the tireless access interface forperforming device-to-device communications in accordance with the firstmode of operation, and

the second communications resources of the wireless access interface forperforming device to device communications in accordance with the secondmode of operation is dependent upon one of a plurality of predeterminedclasses of communications devices.

Paragraph 10. A communications device according to paragraph 8 or 9,wherein the controller is provided with one of a predetermined pluralityof classes, each of the predetermined classes indicating an accessclass, each access class having associated therewith an accessprobability level and a wait time, and the controller is configured incombination with the transmitter to determine in accordance with theaccess probability whether the communications device can transmitsignals via the first communications resources or the secondcommunications resources depending on the received indication at acurrent time, and if the communications device cannot transmit signalsat the current time according to the access probability waiting for thewait time.Paragraph 11. A communications device according to paragraph 8, 9 or 10,wherein the controller is configured in combination with the transmitterand the receiver

to determine in accordance with predetermined conditions whether thecommunications device is within a coverage area for transmitting orreceiving radio signals via the wireless access interface provided by amobile communications network, and

if the communications device is determined to be within the coveragearea of the mobile communications network and has received theindication of communications resources for transmitting signals to oneor more other communications devices, when within a coverage area of themobile communications network, then depending on the indication and theconfiguration of the one or more of the first communications resources,

to transmit the signals to the one or more other communications devicesvia the fast communications resources allocated by the mobilecommunications network in accordance with a first mode of operation, or

depending on the indication and the configuration of the one or more ofthe second communications resources, to transmit the signals to the oneor more other communications devices via the second communicationsresources via the second communications resources in accordance with thesecond mode of operation using the device to device communicationsprotocol, or

if the communications device is determined not to be within the coveragearea of the mobile communications network,

to transmit the signals via the wireless access interface to one or moreother communications devices in accordance with the device to devicecommunications by accessing the first or second communications resourcesor one or more other communications resources of the wireless access inaccordance with a second operating mode of a device to devicecommunications protocol.

Paragraph 12. A communications device according to any of paragraphs 8to 11, wherein the controller is configured in combination with thetransmitter and the receiver to transmit the signals to the one or moreother communications devices via the second communications resources inaccordance with the second mode of operation using the device to devicecommunications protocol by performing a contentious access procedure forthe second communications resourcesParagraph 13. A communications device according to any of paragraphs 8to 11, wherein first communications resources and the secondcommunications resources include one or more communications resourceswhich are the same.Paragraph 14. A communications device according to any of paragraphs 8to 13, wherein the controller is configured in combination with thereceiver

to receive, periodically, from the mobile communications networkinformation identifying at least one of the first communicationsresources of the wireless access interface or the second communicationsresources of the wireless access interface.

Paragraph 15. A method of communicating using an infrastructureequipment forming part of a mobile communications network, the methodcomprising

transmitting signals to communications devices via a wireless accessinterface,

receiving signals from the communications devices via the wirelessaccess interface, and

controlling the transmitting and the receiving to form the wirelessaccess interface, wherein the controlling the transmitting comprises

transmitting an indication to each of one or more of the communicationsdevices identifying whether the communications device is allowed toaccess at least one of

first communications resources of the wireless access interface whichcan be allocated on request to the communications device by theinfrastructure equipment for transmitting signals from the commutationsdevice to one or more others of the communications devices or receivingsignals from the one or more other communications devices in accordancewith the first mode of operation, when the communications device iswithin a coverage area provided by the infrastructure equipment and

second communications resources of the wireless access interface, whichcan be used by the communications device for transmitting signals to oneor more others of the communications devices or receiving signals fromthe one or more other communications devices in accordance with a secondmode of operation using de vice to device communications protocol, whenthe communications device is within the coverage area provided by themobile communications network.

Paragraph 16. A method according to paragraph 15, wherein thetransmitting the indication to each of one or more, of thecommunications devices identifying whether the communications device isallowed to access at least one of the first communications resources orthe second communications resources, comprises

identifying a class of each of the one or more communications devices,

determining, depending on the class of each communications device,whether the communications de vice can have access, to one or more ofthe first communications resources of the wireless access interface orthe second communications resources of the wireless access interface,

generating, for each of the one or more communications devices, theindication as to whether or not the communications device is allowedaccess to one or more of the first communications resources of thewireless access interface or the second communications resources of thewireless access interface depending on the class of the communicationsdevice, and

to transmitting to each of the one or more communications device thegenerated indication for the communications device.

Paragraph 17. A method according to paragraph 16, wherein thetransmitting the indication to each of one or more of the communicationsdevices identifying whether the communications device is allowed toaccess at least one of the first communications resources or the secondcommunications resources, comprises

determining in accordance with predetermined conditions a change onwhether each of the one or more communications devices can have accessto one or more of the first communications resources of the wireless,access interface or the second communications resources of the wirelessaccess interface,

regenerating, for each of the one or more communications devices, inaccordance with the change the indication as to whether or not thecommunications device is allowed access to one or mare of the firstcommunications resources of the wireless access interface or the secondcommunications resources of the wireless access interface depending onthe class of the communications device, and

transmitting to each of the one or more communications device thechanged indication for the communications device.

Paragraph 18. A method of communicating according to any of paragraphs15 to 17, comprising

determining a configuration, of the first communications resources ofthe wireless access interface and the second communications resources ofthe wireless access interface,

generating information identifying the first communications resourcesand the second communications resources, and

transmitting, periodically, to the one or more communications devices,information identifying at least one of the first communicationsresources of the wireless access interface or the second communicationsresources of the wireless access interface.

Paragraph 19. A method of communicating according to any of paragraphs15 to 18, comprising

determining, in accordance with predetermined conditions, a change inthe configuration of the first communications resources of the wirelessaccess interface and the second communications resources of the wirelessaccess interface,

generating information identifying the changed first communicationsresources and the changed second communications resources, and

transmitting, periodically, to the one or more communications devices,information identifying the change of the at least one of the firstcommunications resources of the wireless access interface or the secondcommunications resources of the wireless access interface.

Paragraph 20. A method of communicating according to any of paragraphs17, 18 or 19, wherein the predetermined conditions for changing theindication include an emergency state or a congested state.

Paragraph 21. An infrastructure equipment for forming part of a mobilecommunications network, the infrastructure equipment comprising

a transmitter configured to transmit signals to communications devicesvia a wireless access interface,

a receiver configured to receive signals from to the communicationsdevices via the wireless access interface, and

a controller far controlling the transmitter and the receiver to formthe wireless access interface for transmitting or to receiving thesignals to the one or more communications devices, wherein thecontroller is configured in combination with the transmitter to transmitan indication to each of one or more of the communications devicesidentifying whether the communications device, is allowed to access atleast one of

first communications resources of the wireless access interface whichcan the allocated on request to the communications device by theinfrastructure equipment for transmitting signals from thecommunications device to one or more others of the communicationsdevices or receiving signals from the one or more other communicationsdevices in accordance with the first mode of operation, when thecommunications device is within a coverage area provided by theinfrastructure equipment, or

second communications resources of the wireless access interface whichcan be used by the communications device for transmitting signals to oneor more others of the communications devices or receiving signals fromthe one or more other communications devices in accordance with a secondmode of operation using device to device communications protocol, whenthe communications device is within the coverage area provided by themobile communications network.

Paragraph 22. An infrastructure equipment according to paragraph 21,wherein the controller is configured

to identify a class of each of the one or more communications devices,

to determine, depending on the class of each communications device,whether the communications device can have access to one or more of thefirst communications resources of the wireless access interface or thesecond communications resources of the wireless access interface,

to generate, for each of the one or more communications devices, theindication as to whether or not the communications device is allowedaccess to one or more of the first communications resources of thewireless access interface or the second communications resources of thewireless access interface depending on the class of the communicationsdevice, and the controller is configured in combination with thetransmitter

to transmit to each of the one or more communications device thegenerated indication for the communications device.

Paragraph 23. An infrastructure equipment according to paragraph 22,wherein the controller is configured

to determine in accordance with predetermined conditions a change onwhether each of the one or more communications devices can have accessto one or more of the first communications resources of the wirelessaccess interface or the second communications resources of the wirelessaccess interface,

to re-generate, for each of the one or more communications devices, inaccordance with the change the indication as to whether or not thecommunications device is allowed access to one or more of the firstcommunications resources of the wireless access interface or the secondcommunications resources of the wireless access interface depending onthe class of the communications device, and the controller is configuredin combination with, the transmitter

to transmit to each of the one or more communications device the changedindication for the communications device.

Paragraph 24. An infrastructure equipment according to any of paragraphs21 to 23, wherein the controller is configured

to determine a configuration, of the first communications resources ofthe wireless access interface and the second communications resources ofthe wireless access interface.

to generate information identifying the first communications resourcesand the second communications resources, and the controller isconfigured is combination with the transmitter

to transmit, periodically, to the one or more communications devices,information identifying at least one of the first communicationsresources of the wireless access interface or the second communicationsresources of the wireless access interface.

Paragraph 25. An infrastructure equipment according to any of paragraphs21 to 24, wherein the controller is configured

to determine, in accordance with predetermined conditions, a change inthe configuration of the first communications resources of the wirelessaccess interface and the second communications resources of the wirelessaccess interface,

to generate information identifying the changed first communicationsresources and the changed second communications resources, and thecontroller is configured in combination with the transmitter

to transmit, periodically, to the one or more communications devices,information identifying the change of the at least one of the firstcommunications resources of the wireless access interface or the secondcommunications resources of the wireless access interface.

Paragraph 26. An infrastructure equipment according to any of paragraphs23, 24 or 25, wherein the predetermined conditions for changing theindication include an emergency state or a congested state.

Paragraph 27. A communications device comprising

a transmitter circuitry configured to transmit signals to one or moreother communications devices via a wireless access interface to performdevice-to-device communications,

a receiver circuitry configured to receive signals from the one or moreother communications devices via the wireless access interface, and

a controller circuitry for controlling the transmitter and the receiverto transmit or to receive the signals via the wireless access interfaceto transmit or to receive data represented by the signals in accordancewith a device to device communications, wherein the controller circuitryis provided with at least one of

an indication of one or more first communications resources of thewireless access interface which can be allocated on request to thecommunications device by a mobile communications network fortransmitting signals to one or more other communications devices orreceiving signals from the one or more other communications devices inaccordance with the first mode of operation, when the communicationsdevice is within a coverage area provided by the mobile communicationsnetwork, and

an indication of one or more second communications resources of thewireless access interface which can be used by the communications devicefor transmitting signals to one or more other communications devices orreceiving signals from the one or more other communications devices inaccordance with a second mode of operation using device to devicecommunications protocol, when the communications device is within thecoverage area provided by the mobile communications network, and thecontroller circuitry is configured in combination with the transmittercircuitry and the receiver circuitry

to receive, from the mobile communications network, an indication ofwhether the communications device can use at least one of the firstcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation or the second communications resources of the wireless accessinterface for performing device is device communications in accordancewith the second mode of operation, and

depending on the indication prodded by the mobile communications networkand the configuration of the one or more of the first communicationsresources,

to transmit signals to the one or more other communications devices viathe first communications resources allocated by the mobilecommunications network in accordance with a first mode of operation orreceiving signals from the one or more other communications devices viathe first communications resources, or

depending on the indication provided by the mobile communicationsnetwork and the configuration of the one or more of the secondcommunications resources, to transmit signals to the one or more othercommunications devices via the second communications resources orreceiving signals from the one or more other communications devices viathe second communications resources in accordance with the second modeof operation using the device to device communications protocol.

REFERENCES

-   [1] R2-133840, “CSMA/CA based resource selection,” Samsung,    published at 3GPP TSG-RAN WG2#84, San Francisco, USA, 11-15 Nov.    2013.-   [2] R2-133990, “Network control for Public Safety D2D    Communications” Orange, Huawei, HiSilicon, Telecom Italia, published    at 3GPP TSG-RAN WG2#84, San Francisco, USA, 11-15 Nov. 2013.-   [3] R2-134246, “The Synchronizing Central Node for Out of Coverage    D2D Communication”, General Dynamics Broadband UK, published at 3GPP    TSG-RAN WG2#84, San Francisco, USA, 11-15 Nov. 2013.-   [4] R2-134426, “Medium Access for D2D communication”, LG Electronics    Inc, published at 3GPP TSG-RAN WG2#14, San Francisco, USA, 11-15    Nov. 2013.-   [5] R2-134238, “D2D Scheduling Procedure”, Ericsson, published at    3GPP TSG-RAN WG2#84, San Francisco, USA, 11-15 Nov. 2013.-   [6] R2-134248 “Possible mechanisms for resource selection in    connectionless D2D voice communication”, General Dynamics Broadband    UK, published at 3GPP TSG-RAN WG2#84, San Francisco, USA, 11-15 Nov.    2013.-   [7] R2-134431, “Simulation results for D2D voice services using    connectionless approach”, General Dynamics Broadband UK, published    at 3GPP TSG-RAN WG2#84, San Francisco, USA, 11-15 Nov. 2013.-   [8] “D2D Resource Allocation under the Control of BS”, Xiaogang R.    et al, University of Electronic Science and Technology of China,    https://mentor.ieee.org/802.16/dcn/13/16-13-0123-02-000n-d2    d-resource-allocation-under-the-control-of-bs.docx-   [9] US20130176387-   [10] US20120300662-   [11] LTE for UMTS: OFDMA and SC-FDMA Based Radio Access, Harris    Holma and Antti Toskala, Wiley 2009, ISBN 978-0-470-99401-6.-   [12] Study on LTE Device to Device Proximity Services, Qualcomm    Incorporated, RP-122009.-   [13] EP14153512.0-   [14] EP14153530.2-   [15] EP 09933214

The invention claimed is:
 1. A communications device comprising: atransmitter configured to transmit signals to one or more othercommunications devices via a wireless access interface to performdevice-to-device communications; a receiver configured to receivesignals from the one or more other communications devices via thewireless access interface; and a controller configured, in combinationwith the transmitter and receiver, to control the transmitter and thereceiver to transmit or to receive the signals via the wireless accessinterface to transmit or to receive data represented by the signals inaccordance with a device to device communications, wherein thecontroller is configured to be provided with an indication of one ormore first communications resources of the wireless access interfacewhich can be allocated on request to the communications device by amobile communications network for transmitting signals to one or moreother communications devices or receiving signals from the one or moreother communications devices in accordance with the first mode ofoperation, when the communications device is within a coverage areaprovided by the mobile communications network, and an indication of oneor more second communications resources of the wireless access interfacewhich can be used by the communications device for transmitting signalsto one or more other communications devices or receiving signals fromthe one or more other communications devices in accordance with thesecond mode of operation using device to device communications protocol,when the communications device is within the coverage area provided bythe mobile communications network, and the controller is configured incombination with the transmitter and the receiver to receive, from themobile communications network, an indication of whether thecommunications device can use at least one of the first communicationsresources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation or the second communications resources of the wireless accessinterface for performing device to device communications in accordancewith the second mode of operation; and in a case that the indicationprovided by the mobile communications network indicates that thecommunications device can use the at least one of the firstcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation, transmit signals to the one or more other communicationsdevices via the first communications resources allocated by the mobilecommunications network in accordance with a first mode of operation orreceiving signals from the one or more other communications devices viathe first communications resources, and in a case that the indicationprovided by the mobile communications network indicates that thecommunications device can use the at least one of the secondcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the second mode ofoperation, transmit signals to the one or more other communicationsdevices via the second communications resources or receiving signalsfrom the one or more other communications devices via the secondcommunications resources in accordance with the second mode of operationusing the device to device communications protocol.
 2. Thecommunications device of claim 1, wherein the indication received by thecommunications device of whether the communications device can use atleast one of the first communications resources of the wireless accessinterface for performing device-to-device communications in accordancewith the first mode of operation, and the second communicationsresources of the wireless access interface for performing device todevice communications in accordance with the second mode of operation isdependent upon one of a plurality of predetermined classes ofcommunications devices.
 3. The communications device of claim 1, whereinthe controller is provided with one of a predetermined plurality ofclasses, each of the predetermined classes indicating an access class,each access class having associated therewith an access probabilitylevel and a wait time, and the controller is configured in combinationwith the transmitter to determine in accordance with the accessprobability whether the communications device can transmit signals viathe first communications resources or the second communicationsresources depending on the received indication at a current time, and ifthe communications device cannot transmit signals at the current timeaccording to the access probability waiting for the wait time.
 4. Thecommunications device of claim 1, wherein the controller is configuredin combination with the transmitter and the receiver to: determine inaccordance with predetermined conditions whether the communicationsdevice is within a coverage area for transmitting or receiving radiosignals via the wireless access interface provided by a mobilecommunications network, and if the communications device is determinedto be within the coverage area of the mobile communications network andhas received the indication of communications resources for transmittingsignals to one or more other communications devices, when within acoverage area of the mobile communications network, then depending onthe indication and a configuration of the one or more of the firstcommunications resources, transmit the signals to the one or more othercommunications devices via the first communications resources allocatedby the mobile communications network in accordance with a first mode ofoperation, or depending on the indication and a configuration of the oneor more of the second communications resources, transmit the signals tothe one or more other communications devices via the secondcommunications resources via the second communications resources inaccordance with the second mode of operation using the device to devicecommunications protocol, or if the communications device is determinednot to be within the coverage area of the mobile communications network,transmit the signals via the wireless access interface to one or moreother communications devices in accordance with the device to devicecommunications by accessing the first or second communications resourcesor one or more other communications resources of the wireless access inaccordance with a second operating mode of a device to devicecommunications protocol.
 5. The communications device of claim 1,wherein the controller is configured in combination with the transmitterand the receiver to transmit the signals to the one or more othercommunications devices via the second communications resources inaccordance with the second mode of operation using the device to devicecommunications protocol by performing a contentious access procedure forthe second communications resources.
 6. The communications device ofclaim 1, wherein first communications resources and the secondcommunications resources include one or more communications resourceswhich are the same.
 7. An infrastructure equipment for forming part of amobile communications network, the infrastructure equipment comprising:a transmitter configured to transmit signals to communications devicesvia a wireless access interface; a receiver configured to receivesignals from to the communications devices via the wireless accessinterface; and a controller for controlling the transmitter and thereceiver to form the wireless access interface for transmitting or toreceiving the signals to the one or more communications devices, whereinthe controller is configured in combination with the transmitter totransmit an indication to each of one or more of the communicationsdevices identifying whether the communications device, is allowed toaccess first communications resources of the wireless access interfacewhich can be allocated on request to the communications device by theinfrastructure equipment for transmitting signals from thecommunications device to one or more others of the communicationsdevices or receiving signals from the one or more other communicationsdevices in accordance with the first mode of operation, in a case thatthe communications device is within a coverage area provided by theinfrastructure equipment and the communications device is allowed to usethe first communications resources of the wireless access interface inaccordance with the first mode of operation, and second communicationsresources of the wireless access interface which can be used by thecommunications device for transmitting signals to one or more others ofthe communications devices or receiving signals from the one or moreother communications devices in accordance with a second mode ofoperation using device to device communications protocol, in a case thatthe communications device is within the coverage area provided by themobile communications network and the communications device is allowedto use the second communications resources of the wireless accessinterface in accordance with the second mode of operation.
 8. Theinfrastructure equipment of claim 7, wherein the controller isconfigured to: identify a class of each of the one or morecommunications devices; and determine, depending on the class of eachcommunications device, whether the communications device can have accessto one or more of the first communications resources of the wirelessaccess interface or the second communications resources of the wirelessaccess interface, to generate, for each of the one or morecommunications devices, the indication as to whether or not thecommunications device is allowed access to one or more of the firstcommunications resources of the wireless access interface or the secondcommunications resources of the wireless access interface depending onthe class of the communications device, and the controller is configuredin combination with the transmitter to transmit to each of the one ormore communications device the generated indication for thecommunications device.
 9. The infrastructure equipment of claim 8,wherein the controller is configured to: determine in accordance withpredetermined conditions a change on whether each of the one or morecommunications devices can have access to one or more of the firstcommunications resources of the wireless access interface or the secondcommunications resources of the wireless access interface; andre-generate, for each of the one or more communications devices, inaccordance with the change the indication as to whether or not thecommunications device is allowed access to one or more of the firstcommunications resources of the wireless access interface or the secondcommunications resources of the wireless access interface depending onthe class of the communications device, and the controller is configuredin combination with the transmitter to transmit to each of the one ormore communications device the changed indication for the communicationsdevice.
 10. The infrastructure equipment of claim 9, wherein thepredetermined conditions for changing the indication include anemergency state or a congested state.
 11. The infrastructure equipmentof claim 7, wherein the controller is configured to: determine aconfiguration of the first communications resources of the wirelessaccess interface and the second communications resources of the wirelessaccess interface; and generate information identifying the firstcommunications resources and the second communications resources, andthe controller is configured in combination with the transmitter totransmit, periodically, to the one or more communications devices,information identifying at least one of the first communicationsresources of the wireless access interface or the second communicationsresources of the wireless access interface.
 12. The infrastructureequipment of claim 7, wherein the controller is configured to:determine, in accordance with predetermined conditions, a change in theconfiguration of the first communications resources of the wirelessaccess interface and the second communications resources of the wirelessaccess interface; and generate information identifying the changed firstcommunications resources and the changed second communicationsresources, and the controller is configured in combination with thetransmitter to transmit, periodically, to the one or more communicationsdevices, information identifying the change of the at least one of thefirst communications resources of the wireless access interface or thesecond communications resources of the wireless access interface.
 13. Acommunications device comprising: transmitter circuitry configured totransmit signals to one or more other communications devices via awireless access interface to perform device-to-device communications;receiver circuitry configured to receive signals from the one or moreother communications devices via the wireless access interface; andcontroller circuitry for controlling, in combination with thetransmitter circuitry and the receiver circuitry, the transmitter andthe receiver to transmit or to receive the signals via the wirelessaccess interface to transmit or to receive data represented by thesignals in accordance with a device to device communications, whereinthe controller circuitry is configured to be provided with an indicationof one or more first communications resources of the wireless accessinterface which can be allocated on request to the communications deviceby a mobile communications network for transmitting signals to one ormore other communications devices or receiving signals from the one ormore other communications devices in accordance with the first mode ofoperation, when the communications device is within a coverage areaprovided by the mobile communications network, and an indication of oneor more second communications resources of the wireless access interfacewhich can be used by the communications device for transmitting signalsto one or more other communications devices or receiving signals fromthe one or more other communications devices in accordance with a secondmode of operation using device to device communications protocol, whenthe communications device is within the coverage area provided by themobile communications network, and the controller circuitry isconfigured in combination with the transmitter circuitry and thereceiver circuitry to receive, from the mobile communications network,an indication of whether the communications device can use at least oneof the first communications resources of the wireless access interfacefor performing device-to-device communications in accordance with thefirst mode of operation or the second communications resources of thewireless access interface for performing device to device communicationsin accordance with the second mode of operation, and in a case that theindication provided by the mobile communications network indicates thatthe communications device can use the at least one of the firstcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the first mode ofoperation, transmit signals to the one or more other communicationsdevices via the first communications resources allocated by the mobilecommunications network in accordance with a first mode of operation orreceiving signals from the one or more other communications devices viathe first communications resources, and in a case that the indicationprovided by the mobile communications network indicates that thecommunications device can use the at least one of the secondcommunications resources of the wireless access interface for performingdevice-to-device communications in accordance with the second mode ofoperation, transmit signals to the one or more other communicationsdevices via the second communications resources or receiving signalsfrom the one or more other communications devices via the secondcommunications resources in accordance with the second mode of operationusing the device to device communications protocol.
 14. Thecommunications device of claim 13, wherein the indication received bythe communications device of whether the communications device can useat least one of the first communications resources of the wirelessaccess interface for performing device-to-device communications inaccordance with the first mode of operation, and the secondcommunications resources of the wireless access interface for performingdevice to device communications in accordance with the second mode ofoperation is dependent upon one of a plurality of predetermined classesof communications devices.
 15. The communications device of claim 13,wherein the controller circuitry is provided with one of a predeterminedplurality of classes, each of the predetermined classes indicating anaccess class, each access class having associated therewith an accessprobability level and a wait time, and the controller circuitry isconfigured in combination with the transmitter circuitry to determine inaccordance with the access probability whether the communications devicecan transmit signals via the first communications resources or thesecond communications resources depending on the received indication ata current time, and if the communications device cannot transmit signalsat the current time according to the access probability waiting for thewait time.
 16. The communications device of claim 13, wherein thecontroller circuitry is configured in combination with the transmittercircuitry and the receiver circuitry to: determine in accordance withpredetermined conditions whether the communications device is within acoverage area for transmitting or receiving radio signals via thewireless access interface provided by a mobile communications network,and if the communications device is determined to be within the coveragearea of the mobile communications network and has received theindication of communications resources for transmitting signals to oneor more other communications devices, when within a coverage area of themobile communications network, then depending on the indication and aconfiguration of the one or more of the first communications resources,transmit the signals to the one or more other communications devices viathe first communications resources allocated by the mobilecommunications network in accordance with a first mode of operation, ordepending on the indication and a configuration of the one or more ofthe second communications resources, transmit the signals to the one ormore other communications devices via the second communicationsresources via the second communications resources in accordance with thesecond mode of operation using the device to device communicationsprotocol, or if the communications device is determined not to be withinthe coverage area of the mobile communications network, transmit thesignals via the wireless access interface to one or more othercommunications devices in accordance with the device to devicecommunications by accessing the first or second communications resourcesor one or more other communications resources of the wireless access inaccordance with a second operating mode of a device to devicecommunications protocol.
 17. The communications device of claim 13,wherein the controller circuitry is configured in combination with thetransmitter circuitry and the receiver circuitry to transmit the signalsto the one or more other communications devices via the secondcommunications resources in accordance with the second mode of operationusing the device to device communications protocol by performing acontentious access procedure for the second communications resources.18. The communications device of claim 13, wherein first communicationsresources and the second communications resources include one or morecommunications resources which are the same.